Rooney has so far struggled to make the expected impact in South Africa despite England advancing to the knockout stages. The Manchester United striker failed to hit the target in all three group matches with United States, Algeria and Slovenia.
But Gerrard is convinced the explosive form of the 24-year-old in training is a clear sign Rooney is in the mood to punish England's old rivals. The Liverpool midfielder said: "The pressure is not just on Rooney but all the team - but top players put pressure on themselves. I'm sure Wayne does so in his own spare time.
- Germany v England: LIVE
- Germany v England: Key battles
"But it's only a matter of time before Wayne scores in this tournament and hopefully that is on Sunday. "I have every confidence that he will play well because he played well in the last game and he is looking really sharp in training."
Coach Fabio Capello echoed Gerrard's sentiments about Rooney. The Italian said: "Wayne is training very well and scored a lot of goals. We hope it will be the same. "Always Rooney is a very good player. He didn't score in the last few games but always he is a very important player for us with his movement and everything he does during the game."
Gerrard insists England will be ready for all eventualities - including the last 16 meeting going to penalties. England suffered the heartbreak of losing the 1990 World Cup and Euro 96 semi-finals to Germany on spot-kicks.
He said: "We are very confident going into the game. We are on the back of a good performance against Slovenia. "The mood is good, we have prepared hard for this game and we will do whatever it takes to get across the line into the last eight.
"It is going to be a very difficult game. Ideally we want to win the game in 90 minutes but if we have to go to extra-time and penalties, we will be ready."
Capello has faith in his players to deliver the victory millions of supporters back in England are hoping for. He said: "It is a very important game, one of the more important, because we want to go forward and play the next game.
"I know the value of Germany but I also know the value of my players."
Germany coach Joachim Low failed to show up for the official press conference and no player was present either - contrary to FIFA regulations - with goalkeeping coach Andreas Kopke conducting the briefing.
There was speculation that Germany were angry at not being allowed to train on the Free State Stadium pitch. Instead they used the facilities at a nearby university complex before the press conference.
Kopke said: "This is not a protest at all. People were not able to get here on time.
"We were not able to use the stadium. We had to use another site and tried to be punctual (for the press conference)."
When pressed on what will be viewed as a snub by Low, Kopke became irritated. He said: "We were not able time-wise to get here. We want to be well prepared, that is the reason.
"We were not able to practice on the pitch for logistics reasons. But it is the same for England. We are used to it. We did not practice in the actual stadium the last two times.
"It is not a protest, that's the way it is. There is no point in asking the question again and again."
Kopke is well informed about penalties, should it come to that again when a place in the quarter-finals is at stake. He saved Gareth Southgate's effort for England in the semi-final at Euro 96, on the way to his team winning the championship. Kopke has no fears that current number one Manuel Neuer will rise to the challenge if needed.
Kopke said: "I think it would be great not to have to go to a penalty shoot-out. If we have to go for it, we are prepared. Manuel will of course get the info he needs. But I am not going to give any secrets away.
"We practise penalties but cannot simulate this situation. You have got 120 minutes behind you, the atmosphere is completely different."
While Bastian Schweinsteiger and Jerome Boateng have both trained they remain doubtful through injury while Cacau will be absent after suffering an abdominal muscle strain. Kopke said: "We will have to talk to our doctors and see if they can play. They need to be at 100% in terms of fitness."